Mixed Solvent Of Dimethylformamide Research Articles

Solvent Engineering for Controlled Crystallization and Growth of All-Inorganic Pb-Free Rudorffite Absorbers of Perovskite Solar Cells.

Solution-processed Ag-Bi-I rudorffites with direct band gaps of <2 eV show promise for highly efficient and cost-effective Pb-free solar cells. However, relatively fast crystallization rates of Bi-based films and limited solubility of BiI3 in many solvents result in poor film morphologies, inhibiting their device performance. Here, we conduct a solvent-engineering method to adjust the dynamics of nucleation and growth during film formation. We fabricate Ag2BiI5, AgBiI4, and AgBi2I7 absorber layers using a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) and find that a volume percentage of 50% DMSO causes highly uniform and dense perovskite films via a BiI3-DMSO-AgI intermediate phase formation, leading to solar cells with an improved power conversion efficiency of 0.62% for the Ag2BiI5 absorber. These results provide valuable insights into the optimization of the solution processing technique to realize low-toxicity and efficient perovskite solar cells.

Preparation and Properties of Benzylsulfonyl-Containing Silicone Copolymers via Ring-opening Copolymerization of Macroheterocyclosiloxane and Cyclosiloxane.

Ring-opening copolymerization (ROCP) of benzylsulfonyl macroheterocyclosiloxane (BSM) and five different cyclosiloxanes was systematically investigated. A general approach for the synthesis of benzylsulfonyl-containing silicone copolymers with various substituents, including methyl, vinyl, ethyl, and phenyl, was developed herein. A series of copolymers with variable incorporation (from 6 % to 82 %) of BSM were obtained by modifying the comonomer feed ratio and using KOH as the catalyst in a mixed solvent of dimethylformamide and toluene. The obtained copolymers exhibited various composition-dependent properties and unique viscoelasticity. Notably, the surface and fluorescent characteristics as well as the glass transition temperatures of the copolymers could be tailored by varying the amount of BSM. Unlike typical sulfone-containing polymers, such as poly(olefin sulfone)s, the prepared copolymers displayed excellent thermal and hydrolytic stability. The universal strategy developed in the present study provides a platform for the design of innovative silicone copolymers with adjustable structures and performance.

Titanium dioxide-modified polyetherimide nanofiber membrane for water treatment

The main objective of this work is to fabricate and characterize a new type of nanocomposite nanofiber membrane by incorporating photocatalytic nanomaterials – titanium dioxide (TiO2) into a highly porous nanofiber made of UV-resistant polyetherimide (PEI). The nanofiber membrane was fabricated via an electrospinning method using a dope solution containing 15 wt% PEI dissolved in a mixed solvent of dimethylformamide (DMF)/n-methyl-2-pyrrolidone (NMP). The resultant PEI nanofiber membrane was further modified by coating its surface with TiO2 (0.2 and 0.6 wt%) using electrospraying method. The properties of the TiO2-modified PEI nanofiber membranes were then analysed using scanning electron microscope (SEM), water contact angle (WCA) goniometer and tensile strength machine. Results showed that 0.2 wt% TiO2-modified PEI nanofiber displayed better behaviour by reducing WCA of unmodified nanofiber from 130.25° to 23.35° and improving water flux by 28%. Although the WCA of membrane was further reduced when a higher TiO2 amount (0.6 wt%) was used, the resultant nanofiber suffered from decreased ultimate strength and significant nanoparticles leaching. Using the best performing 0.2% TiO2-modified PEI membrane, significant removal rate of Escherichia coli (99%) and humic acid (∼80%) could be achieved along with 85% methylene blue degradation during photocatalytic process. The findings of this work provide an insight into the design of advanced nanocomposite nanofiber membrane for photocatalytic process.

CO2 -Induced Morphological Transition of Co-Assemblies from Block-Random Segmented Polymers.

The co-assembly process is an effective approach to construct hierarchically nanostructured soft materials, but morphological transition of co-assemblies upon external stimuli, particularly the "green" trigger CO2 , is not unraveled yet. Here, a segmented copolymer, poly(styrene)-block-poly[(4-vinyl pyridine)-random-((2-(diethylamino)ethyl methacrylate)] (P1), is used to co-assemble in the mixed solvent of dimethyl formamide and water with poly(ethylene oxide)-block-poly[(4-vinyl pyridine)-random-((2-(diethylamino)ethyl methacrylate)] (P2) and poly(ethylene oxide)-block-poly(acrylic acid) (P3), respectively. It is found that Janus micelles are generated from the P1-P2 pair in the presence of ferric ion, while wormlike micelles are formed from the P1-P3 duad. Upon stimulation with CO2 , Janus and wormlike aggregates are transferred into core-shell and spherical micelles, respectively.

Corrosion behavior and microstructure of electrodeposited nano-layered Ni–Cr coatings

A successful electroplating process has been developed to make crack-free Ni–Cr coatings. A single bath with a mixed solvent of dimethylformamide (DMF) and water into which a low toxic solute of Cr(III) and Ni(II) salts is dissolved serves for the electroplating operation. Electrochemical measurements presented here offer new insights into the predominant function of DMF in promoting high quality and crack-free formation of Ni–Cr coatings. Representative images of crack-free Ni–Cr multilayer coatings in both nanometer and micrometer scales illustrate the ability to control thickness and composition of the coatings simply through adjusting current density and deposition time in the DMF-mixed bath.

Effect of Solution Properties on Electrospun Chlorinated Polyvinyl Chloride Nanofibers

A kind of novel biodegradable Chlorinated Polyvinyl Chloride (CPVC) nanofibers using a mixture of Dimethyl Formamide (DMF) and Tetrahydrofuran (THF) as solvent were prepared by electrospinning process in this paper. The morphology of electrospun CPVC nanofiber nonwovens were investigated by scanning electron microscopy (SEM). Results indicated that the morphology and diameter of the electrospun fibers were influenced by CPVC solution concentration and the THF amount in the mixed solvents, and the finer and uniform nanofibers were electrospun from a mixed solvent of DMF and THF with ratio of 3/1(w/w).

Solvent effect on the construction of two microporous yttrium–organic frameworks with high thermostability viain situ ligand hydrolysis

Two novel yttrium trimesates with open frameworks have been synthesized by the self-assembly of trimethyl 1,3,5-benzenetricarboxylate and Y(3+) ion in mixed solvent of dimethylformamide (DMF)/water and diethylformamide (DEF)/water, where changes of solvents with different molecular sizes lead to the formation of two similar three-dimensional frameworks with different spatial arrangement styles of the linkers around the Y(3+) centers, and solvent-dependent one-dimensional channels (ca. 6.2 x 7.7 A(2)) along the [100] direction, as shown by X-ray crystallography. Structural analyses indicate that they have excellent thermal stabilities which are endurable up to 490 degrees C.

Facile Fabrication of Spindle-shaped β-FeOOH/PAN-amidhydrazone/Ag Core-Shell Particles in Organic Solvent

The spindle-shaped β-FeOOH/polyacrylonitrile-amidoxime (PAN-amidhydrazone)/silver composite particles with a stable core-shell structure were successfully fabricated in the mixed solvent of dimethylformamide (DMF) and methanol using a seed-mediated growth technique, where metal silver nanoparticles tethered on β-FeOOH served as the nucleation sites for the growth of the silver nanoshell overlayer. The closed silver shell was finally formed after the seed catalyzed growing process repeated several cycles. The results of transmission electron microscopy (TEM) showed that the composite nanoparticles were spindle-shape. The resulting nanoparticles showed good stability under various conditions.

Micropatterns of Ag2Se Nanocrystals

Silver selenide (Ag 2 Se) nanocrystals were synthesized solvothermally using a single source precursor silver selenite (Ag 2 SeO 3 ) in the presence of dimethyl formamide (DMF) in an autoclave. The effect of time and temperature on the crystalline and morphological behavior of the products was investigated. The interaction of Ag 2 SeO 3 with DMF resulted in the formation of Ag 2 Se nanoparticles, whereas mixed solvent of DMF and a few aliphatic alcohols (1:1 (v/v), at 165°C for 24 h) yielded novel microstructures. The mixed combination containing methanol-DMF yielded fractal-like morphology, while hollow needle-shaped structures resulted from a ethanol-DMF mixture. Rod shaped structures having riblike morphology were obtained from propanol-DMF mixed solvent.

Liquid-liquid equilibria for the extraction of aromatics from naphtha reformate by dimethylformamide/ethylene glycol mixed solvent

The phase equilibria for the extraction of aromatics from naphtha reformate (b.p. 60–135°C) in a mixed solvent of dimethylformamide (DMF) and ethylene glycol (EG) have been correlated using the UNIFAC group contribution model. The interaction parameters of DMF and EG with different hydrocarbon groups present in the reformate, such as CH 2 (paraffinic CH 2), ACH (aromatic CH) and ACCH 2 (aromatic CCH 2), and each of the two solvents were fitted to experimental concentrations of ternary systems containing these groups. The extraction runs were carried out at different temperatures, solvent compositions and solvent-to-feed ratios. The experimental results compared favorably with those predicted from the UNIFAC method. The minimum required energy for separation was achieved at 57°C using a 44% EG solvent with a solvent-to-feed ratio of 2.2 on a volume basis.